Method and apparatus for making hollow bodies of concrete or the like

ABSTRACT

Pipes having dense, watertight concrete walls are produced by vibrating a rotating mould suspended on a roller shaft as the mold is being filled, and continuing its rotation without vibration for a short time after the mold is filled. Vibration is attained by ridges or fingers which can be made effective, or not, to vibrate the mold as it is rotating. In one form, fingers on a roller shaft are slidable between ineffective positions and positions where they serially engage a smooth running surface on the mold. In other forms, a mold is movable from a position where it is supported by engagement of a ridged running surface on either the roller shaft or the mold with a cylindrical surface on the other to a position where the cylindrical surface on the mold runs on the roller shaft or on an auxiliary sleeve without vibration.

United States Paten Danko [151 3,642,413 [451 Feb. 15, 1972 METHOD AND APPARATUS FOR MAKING HOLLOW BODIES OF CONCRETE OR THE LIKE Douglas ..;.25/30 c Primary Examiner.l. Spencer Overholser Assistant Examiner-De Walden W. Jones Att0rneyGeorge F. Des Marais [57] ABSTRACT Pipes having dense, watertight concrete walls are produced by vibrating a rotating mould suspended on a roller shaft as the mold is being filled, and continuing its rotation without vibration for a short time after the mold is filled. Vibration is attained by ridges or fingers which can be made effective, or not, to vibrate the mold as it is rotating. in one form, fingers on a roller shaft are slidable between ineffective positions and positions where they serially engage a smooth running surface on the mold. in other forms, a mold is movable from a position where it is supported by engagement of a ridged running surface on either the roller shaft or the mold with a cylindrical surface on the other to a position where the cylindrical surface on the mold runs on the roller shaft or on an auxiliary sleeve without vibration.

9 Claims, 6 Drawing Figures METHOD AND APPARATUS FOR MAKING HOLLOW BODIES OF CONCRETE OR THE LIKE This invention relates to a method and machines formanufacturing pipes and other tubular bodies having dense, watertight walls of concrete.

Various machines employing different manufacturing methods are used for manufacturing concrete pipe sections and other tubular structures. Each of the different methods and machines in use involve certain physical or mechanical limitations which limit them to making pipe sections of a given size, wall thickness and strength. A method for producing concrete pipes of good quality utilizes a machine which is sometimes referred to as a roller suspension machine. A

machine of this type consists essentially of a hollow mold having. running. rings supported on a roller shaft extending through the rings and the mold to rotatably suspend the mold on the rollershaft. A fresh concrete mix is fed into the mold as the roller shaft and the mold rotate. The rotating mold and the roller shaft function to distribute and compact the concrete mix. Examples of machines employing such a method for forming hollow bodies of concrete are described in the US. Pat. Nos. 2,795,026, granted June 11, 1957, and 2,829,418, granted Apr. 8, 1958. The basic roller suspension method is satisfactory for producing thin wall, small diameter pipes suitable for lines for transmitting water at low pressure, and pipes which are customarily used for sewer and culvert purposes.

The use of conventional roller suspension machines for manufacturing pipes having thicker walls, particularly large diameter pipes, and for manufacturing high-pressure pipes which are reinforced with embedded steelcages; longitudinal rods, or prestressed wires, sometimes presents difficulties in the production of sound pipes free of defects such as porosity, cracks, separations, voids, or honeycomb near steel reinforcements. These and other faults may result in rejects, hand patching and other costly repairs.

Even with strict control over the selection and use of the concrete materials and close supervision of all manufacturing operations, conventional roller suspension machines do not always produce high-pressure pipes of large diameter with consistent watertightness. I

It is amongthe objects of the present invention to enlarge upon the utility of the basic roller suspension technique; to provide watertight high-pressure pipe, and to provide a method and machines for making concrete pipes by which the troublesome faults hereinabove mentioned are avoided.

Another object is to produce roller suspension, reinforced concrete pipe with the concrete adjacent its outer surface compacted to a degree substantially a'sgreat as the concrete nearer to its inner surface.

Another object is to enable the making of large, thick wall pipe of which the still plastic though highly compacted concrete mix at the interior surface thereof will not-require supplemental finishing after the pipe has been molded on a roller suspension machine.

According to the invention, a suspended mold and its contents are vibrated vertically as the mold is turning on its supporting roller shaft. This may be accomplished as by providing ridges, or flats, spaced at equal intervals, to sequentially lift and drop a running ring attached to the mold as the mold rotates. The ridges or flats may be located adjacent both ends of the mold or at either end, and on either the roller shaft or on the inner periphery of one or of both of the running rings. The rate of vibration of the mold depends upon the speed of the roller shaft, its diameter and the spacing of the ridges or flats. The amplitude of vibration is governed by the height of the ridges. Effective results have been obtained with ridge heights of one-sixteenth inch and of one-eighth inch for making pipes of various sizes. As an example, experience has demonstrated that in making 48-inch diameter low-pressure pipes on a machine havinga lO-inch diameter roller shaft with I welded ridges of one-eighth inch height, spaced equally around the shaft, andwith the shaft rotating at a speed to produce 3,800 vibrations per minute, greatly improved consolidation of the concrete resulted. A gain of about 25 percent in the average compressive strength of core specimens taken from the pipe wall over the compressive strength of like specimens taken from a similar pipe which has been made on a conventional roller suspension machine was found. In addition, the compressive strength improvement was accomplished in one-half of the rolling time required on a conventional roller suspension machine Comparable improved results and advantages were obtained in the production of 60. 66 and 72 inch diameter pipes.

Another important feature is the addition of means for reducing the vibration to zero toward the terminus of a rotating cycle or as deceleration of the mold is taking place. This control minimizes the possibility of fallouts" or the shaking loose and falling of areas of still plastic concrete from the crown of the inner surface of a molded pipe at' the completion of the cycle. A further beneficial advantage is achieved by providing removable ridge members so that the height of the ridges can be changed to provide the amplitude of vibration most suitable for effecting an optimum compaction in pipes of different sizes.

The foregoing and other objects, features and advantages of the invention and preferred ways of practicing it will be evident from the following description of illustrative embodiments thereof and from the accompanying drawing.

In the drawing, 1

FIG. 1 is a side elevation of a roller suspension machine embodying the present invention;

FIG. 2 is an enlarged longitudinal section of the right end of the roller shaft shown in FIG. 1;

FIG. 3 is a cross-sectional view on line 3-3 of FIG. 2, showing a group of ridge members;

FIG. 4 illustrated an embodiment of the invention using a modified mold running ring; and

FIGS. 5 and 6 illustrate still other embodiments of the invention.

The roller suspension machine illustrated in FIG. 1 includes a roller shaft 10 and a hollow cylindrical mold II which is supported on the shaft and rotated thereby as the shaft is driven. In its simplest form the mold is constituted of an outside cylindrical shell 12 removably attached to a pair of mold end-rings l3, 14, which bear and run on the roller shaft. The suspended mold and its contents are rotated as the shaft turns. As is well understood in the art, the various mold parts may take any of a variety of forms to accomplish the molding of hollow bodies of different shapes, suchas bell and spigot pipes, double-spigot pipes, double-bell pipes, or plain-ended cylinders with square or bevelled ends, for example, and the mold may be provided with means to support therein any of the various types of steel reinforcements commonly employed in making concrete pressure pipes, such assteel cages and longitudinally extending rods or prestressed wires.

Referring to FIG. 1, the roller shaft 10 is made up of four main sections rigidly connected end to end, a stub shaft [5 and three tubular sections 16, 17 and 18.

An enlarged portion 19 at the base of the stub shaft 15 is welded to the tubular section 16. The tubular sections 16 and 17 are joined by bolts 20 which engage flanges on the respective sections 16 and 17 and also hold a wear ring 21 in place.

The stub shaft 15 is journaled in a selfaligning, thrust-resisting roller bearing 22 supported on a post 23.

The other end of the tubular section 17 is fitted into a socket 24 in the adjacent end of the tubular section 18, as best seen in FIG. 2. A flange 25 on the tubular section 17 is buttressed against a flange 26 on the tubular section 18 by a pair of clamping rings 27, 28 engaged by a number of bolts 29 distributed around the rings. The bolts also hold a wear ring 30 in place against the ring 27. The wear rings 21 and 30 are of such size as to be engageable with the end rings of the mold to restrict endwise movement of the mold on a roller shaft.

The roller shaft I0 is driven by a chain or belt 3] which is driven by a motor 32. The shaft is rotatably supported at one end by the roller bearing 22. Its other end has a journal-33 which is cradled on rollers at either side of the shaft, of which one is shown at 34 in FIG. 1. Trunnions on the roller are supported by a pair of bearings 35, which are mounted on a horizontal arm or gate 36. The roller which engages the journal at the other side of the roller shaft is similarly mounted on the arm.

The arm 36 is pivotally supported on a hinge 37 attached to a post 38 located at the far side of the roller shaft, and its free end normally rests upon a post 39 to which it is locked when the machine is readied for operation.

Each time a mold is replaced on the roller shaft it is necessary to swing the arm 36 outwardly from beneath the journal 33. Before this can be done an auxiliary force must replace the supporting force provided by the arm in order to prevent the roller shaft from tipping downwardly. Tipping of the roller shaft is prevented by a chain 40 which forms a loose loop under the roller shaft that can be brought up to support the shaft in a horizontal position. One end of the loop 40 is attached to a bracket 41 on a stationary frame and its other end is attached to a piston rod 42 of a hydraulic cylinder 43 which is actuatable to take up on the loop whenever it is necessary to use the loop to support the roller shaft.

Vibration of a mold is attained by ridges evenly spaced around the roller shaft opposite to the inner periphery of either one or of both mold rings. As better shown in FIGS. 2 and 3. a selected number of ridge members or fingers 45 are individually mounted for sliding radially in a like number of slots 46 in the wall of the tubular section 17 of the roller shaft. Each finger has a laterally widened footing 47 with a base face inclined longitudinally in relation to the axis of theroller shaft and engaging the exterior conical surface 48 of a wedge or camming member 49. Shoulders 50 on the footing of each ridge member are engageable with the interior surface of the tubular section 17 to limit the height of projection of the fingers above the outer rolling surface of the roller shaft.

As shown in FIG. 2, the position of the camming member 49 is such as to hold all of the fingers in their most extended positions with their heads projecting outward beyond the rolling surface of the roller shaft. The height of the narrow finger portions of the ridge members 45 above the shoulders 50 and the distance of their projection beyond the outer surface of the roller shaft determines the amplitude of vibration of the mold. The amplitude may be changed by substituting a set of fingers of another predetermined height.

By shifting the camming member 49 to the right (FIG. 2) the fingers 45 are released and free to move radially inwardly in their slots to position their heads at the outer surface of the roller shaft so as not to interfere with smooth, vibrationless rotation of the mold.

The longitudinal movements and finger-holding position of the camming member 49 are achieved by an hydraulic system including a pressure cylinder 51. A rod 52, which is anchored to a spider 53 attached by welding to the camming member 49, is directly connected to the piston rod 54 of the pressure cylinder 51 by a rod-end, self-aligning coupler 55.

The cylinder is maintained axially immovable by a ball joint 56 connected at one end to a plate 57 closing the end of the tubular section l8, and pivotally connected at its other end to a clevis 58 fixed to the cylinder 51.

The pressure at opposite ends of the cylinder 51 is maintained and varied by an hydraulic system including conduits 60 and 61 connecting respectively with separate passageways through a rotary seal 62 which connect, respectively, with hoses 63 and 64. The latter lead from a directional control valve 65 connected to a supply line 66 and a return line 67. Fluid pressure is developed by a pump (not shown) having its discharge connected to the supply line.

The hoses 63, 64, and the member 68 of the rotary seal 62 remain stationary or free as the roller shaft rotates. The member 68 is supported on an antifriction bearing on a central hub extending from a block 69 which is bolted to a disk 70 fastened to the plate 57 by bolts 71. The separate passageways through the rotary seal are diagrammatically indicated with broken lines. A suitable rotary seal illustrated is manufactured by the Fawick Corporation of Cleveland, Ohio U.S.A., but any other conventional rotary seal may be used to transmit fluid pressure between the conduit 60 and the hose 63 and between the conduit 61 and the hose 64.

A set of ridges coacting between the roller shaft and one of the running rings of a mold will bring about improved compaction and sound large diameter, thick wall pipe. However. two sets of ridges for coacting with the running rings at both ends of a mold are beneficial, particularly for producing pipes in lengths longer than the standard lengths of commercial pipes heretofore made with conventional roller suspension machines. This is a highly important advantage because pipe lines constituted of long pipe sections can be less costly than pipe lines constituted of shorter pipe sections and more joints.

The machine illustrated in FIG. 1 has a set of ridge members 73 for serially engaging the inner periphery 74 of the end-ring 13. They correspond in size, number, spacing, height and alignment with the ridge-members 45 opposite the end-ring 14.

The ridge members 73 are adjustable radially in their slots in the tubular section 17 and are supported in fixed positions by a tapering camming member (not shown) which is a duplicate of the camming member 49 shown in FIG. 2. The camming member engaging the ridge members 73 is connected to the camming member 49 by a rod 75 so that the two camming members may move simultaneously to effect the same positioning of their respective sets of ridge members 45 and 73.

A normal operating procedure involves running the machine and charging the mold while the mold is vibrating. In this manner the vibration is immediately effective to initiate distribution and consolidation of that portion of the mix which is to be near to the outside wall of the mold and about steel reinforcements. A mix having a moisture content range from about 5 to 6 percent by weight of dry materials has been used successfully in making large diameter, thick wall pipes, and a relatively wetter mix may be used for making a thin-walled pipe. The drier a mix the less workable -it is because of its harshness, but the vibration of the mold by the interactionof the mold with the rotating shaft makes it possible to usea relatively dry mix. This results in improving the density of the wall of the pipe. Owing to the greater compaction obtainable,

sound large diameter, thick wall pipe having a wall thickness greater than that expressed by the formula D divided by 12:, where D is the diameter of the pipe in inches, can be produced with much greater consistency than heretofore.

Vibration of the mold is continued as the mold is charged and until it is filled. During this period, and when the mold is full, vibration augments the action of the roller shaft to bring about greater compaction of the mix than would occur if only the pressing force of the roller shaft were relied on.

After the mold is filled, the hydraulic cylinder 51 is actuated to draw the camming members toward the cylinder. This action results in the descent of the ridge members and attendant gradual lessening of the amplitude of vibration to zero. The mold is allowed to rotate steadily on the roller shaft for a short time and only as long as necessary to insure the continuity and smooth finishing of the interior surface of the molded concrete body.

Another mode for vibrating a mold is illustrated in FIG. 4. It

includes a mold with a mold ring 76 having a ridged running surface 77 and a smooth running surface 78. The diameter of.

the surface 78 is sufiiciently large to clear the roller shaft 79 when the ring is supported on the shaft by engagement of the ridged running surface therewith. The ring 76 may be raised onto an exterior cylindrical surface 80 of a sliding sleeve to clear the ridges 81 from engagement with the roller shaft 79. As shown in FIG. 4, the mold will vibrate as the mold and the shaft rotate owing to the sequential engagement of the ridges 81 with the shaft 79. Sloping surfaces 82, 83 on the end ring and the sleeve are engageable to slide the mold ring onto the sleeve as the sleeve is advanced toward the mold.

With the smooth running surface 78 bearing on the sleeve, the mold will rotate steadily without vibration. The sleeve may be translated along the roller shaft by any suitable means such as a yoke 84 for engaging the flanges 85, 86 thereof.

As is evident from the embodiments illustrate in FIG. 6, a running ring 76 ofa mold 11 may have a smooth running surface K to bear upon a roller shaft 79' and a ridged running surface with ridges 81 and with an inner periphery of greater diameter than that of the smooth running surface so that the ridged running surface may be engaged by a slidable sleeve 80 to cause vibration of the mold. When the sleeve is withdrawn from under the ridged running surface the mold will be supported on the rotating shaft 79' by engagement therewith of the smooth running surface 78. The position of the sleeve axially of the running surfaces may be adjusted by an suitable means such as have been described hereinabove.

The embodiment illustrated in FIG. 5 is still another mode for producing vibration. An annular groove 87 is formed in a roller shaft 88 at a location where it will be opposite a smooth running surface 89 on a mold ring 90. Ridges 91 are welded to the bottom of the groove. By making the height of the ridges and the depth of the groove substantially equal, the mold can be slid endwise along the shaft to position the running surface 89 of the mold ring into the cylindrical surface of the shaft to allow the mold to rotate without vibration.

it is to be understood that the foregoing disclosure relates only to preferred embodiments of the invention and that numerous modifications and alterations may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

1. Apparatus for molding a plastic and subsequently hardenable material, said apparatus comprising a hollow cylindrical mold having running rings supported on a roller shaft extending through said rings and said mold to rotatably suspend the mold on the roller shaft, means for rotating said mold and said shaft, and means interacting on the shaft and at least one of said running rings for vibrating said mold by repetitiously lifting and dropping the mold relative to the shaft as the shaft and the mold rotate.

2. Molding apparatus according to claim 1, said vibrating means comprising ridge members coacting between said roller shaft and the inner periphery of at least one of said rings to vibrate said mold as the roller shaft and the mold rotate.

3. Molding apparatus according to claim 2, wherein said ridge members project outwardly from the outer surface of said roller shaft at equal intervals around the roller shaft.

4. Molding apparatus according to claim 2, including means for adjusting said ridge members laterally to the axis of rotation of said roller shaft to render them effective or ineffective to vibrate said mold.

5. Molding apparatus according to claim 2, wherein said roller shaft has an annular groove wider than the inner periphery of said one of said rings, said ridge members being attached to the bottom of said groove.

6. Molding apparatus according to claim 2, wherein at least one of said rings has at the inner periphery thereof a smooth running surface facing said roller shaft, said ridge members spaced around said ridged surface and extending radially inwardly to a circle having a diameter less than the diameter of said smooth running surface, a sleeve slidably mounted on said roller shaft, said sleeve having a cylindrical surface for engaging said smooth running surface to support said ridged running surface clear of the roller shaft, and means to actuate said sleeve into and out of engagement with said smooth running surface.

7. Molding apparatus according to claim 2, wherein said roller shaft comprises a tubular section and said ridge members are slidable in slots in said section, and means for positioning said ridge members to locate their heads outside of the circumference of said tubular section.

8. Molding apparatus according to claim 7, wherein said positioning means comgrise camming means in sliding contact with said ridge mem ers, and means for actuating said camming means, said actuating means comprising a pressure cylinder.

9. Molding apparatus according to claim 1 wherein at least one of said running rings has ridged and smooth internal running surfaces axially adjacent, of which the outermost surface with respect to the axis of the mold has a larger diameter and does not contact the roller shaft, and an axially movable sleeve on the roller shaft which can be slid to engage the outermost surface to thus disengage the innermost surface from the roller shaft. 

1. Apparatus for molding a plastic and subsequently hardenable material, said apparatus comprising a hollow cylindrical mold having running rings supported on a roller shaft extending through said rings and said mold to rotatably suspend the mold on the roller shaft, means for rotating said mold and said shaft, and means interacting on the shaft and at least one of said running rings for vibrating said mold by repetitiously lifting and dropping the mold relative to the shaft as the shaft and the mold rotate.
 2. Molding apparatus according to claim 1, said vibrating means comprising ridge members coacting between said roller shaft and the inner periphery of at least one of said rings to vibrate said mold as the roller shaft and the mold rotate.
 3. Molding apparatus according to claim 2, wherein said ridge members project outwardly from the outer surface of said roller shaft at equal intervals around the roller shaft.
 4. Molding apparatus according to claim 2, including means for adjusting said ridge members laterally to the axis of rotation of said roller shaft to render them effective or ineffective to vibrate said mold.
 5. Molding apparatus according to claim 2, wherein said roller shaft has an annular groove wider than the inner periphery of said one of said rings, said ridge members being attached to the bottom of said groove.
 6. Molding apparatus according to claim 2, wherein at least one of said rings has at the inner periphery thereof a smooth running surface facing said roller shaft, said ridge members spaced around said ridged surface and extending radially inwardly to a circle having a diameter less than the diameter of said smooth running surface, a sleeve slidably mounted on said roller shaft, said sleeve having a cylindrical surface for engaging said smooth running surface to support said ridged running surface clear of the roller shaft, and means to actuate said sleeve into and out of engagement with said smooth running surface.
 7. Molding apparatus according to claim 2, wherein said roller shaft comprises a tubular section and said ridge members are slidable in slots in said section, and means for positioning said ridge members to locate their heads outside of the circumference of said tubular section.
 8. Molding apparatus according to claim 7, wherein said positioning means comprise camming means in sliding contact with said ridge members, and means for actuating said camming means, said actuating means comprising a pressure cylinder.
 9. Molding apparatus according to claim 1 wherein at least one of said running rings has ridged and smooth internal running surfaces axially adjacent, of which the outermost surface with respect to the axis of the mold has a larger diameter and does not contact the roller shaft, and an axially movable sleeve on the roller shaft which can be slid to engage the outermost surface to thus disengage the innermost surface from the roller shaft. 